1) Field of the Invention
The present invention relates to a fabric seam which is impervious to fluids. The seam is ultrasonically formed in a polyurethane-polyester laminated fabric and is principally intended to be used to construct surgical, precautionary and laboratory garments. However, the present invention is equally applicable to other uses such as rainwear, tarpaulins and laundry bags. Thus, the scope of the invention covers the fabric seam, a method for making the same, and garments made with the seam.
(2) Description of the Related Art
Various prior art seams and garments have been developed to shield wearers from hazardous environments. However, with the current heightened awareness of infectious disease, such as Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV), spread by contact with bodily fluids, this technology is of ever-increasing importance, particularly in the field of surgical, precautionary and laboratory garments. Many operations such as cesarean sections, cardiovascular surgery, orthopedic surgery and others expose surgical staff to large quantities of bodily fluids and thereby expose them to health risks. Without proper protection, the risk of contracting infectious disease is significantly increased.
Due to the enormity of the consequences if not the magnitude of the risk, the health-care profession must have reliable protection to prevent contact with bodily fluids. Thus, the protective garments must be absolutely impervious to fluids at least in those areas of the garment likely to come into contact with bodily fluids. In addition, many tasks performed by surgical personnel are physically demanding such that large and repetitious forces are exerted upon the garments they wear. Thus, the protective garments must be fairly strong and fatigue resistant to withstand the rigors of the surgical environment.
As a practical matter, the surgical garments must be either inexpensive and disposable or capable of sterilization and re-use. In reality, protective garments which are a few times more expensive, but capable of being used many more times before being retired are more cost effective. However, in order to be reusable, the garments must be capable of sterilization. The most common method of sterilization is by steam autoclaving which subjects the garments to temperatures in excess of 275.degree. F. Thus, the garments must be capable of withstanding a minimum of 275.degree. F. in order to take advantage of the inherent economy of multiple usage.
In the past, some surgical garments have been developed to overcome these problems. For instance, U.S. Pat. No. 5,003,902 discloses a surgical garment constructed with stitched seams sealed with a thermo-setting adhesive in order to make them fluid-tight. By using this two-step process, garments can be made having strong, fluid-tight seams. Neither of the processes alone would produce a suitable garment. Without the stitching, the seam would not withstand the rigors of the surgical environment, and without the adhesive, the garment would not be fluid-tight.
A similar seam is disclosed in U.S. Pat. No. 4,272,851 in which the garment seams are ultrasonically sealed and then stitched for reinforcement. The end result is a disposable garment. The material used is a polyethylene-coated, non-woven, spunbonded, olefin material. In addition, either step of the process of forming the garment used alone yields unacceptable results. The ultrasonic welding used alone produces an inferior seam having low tensile strength. Thus, reinforcement by stitching the seam is necessary. Stitching alone leaves voids in the garment at the seams, thus potentially exposing the user to fluids and health risks.
Other prior art seams have the same problems. Moreover, these problems are not limited to surgical garments. These problems exist in other applications such as raincoats, jackets, and similar outerwear as well as tents, outdoor equipment, tarpaulins and the like. Likewise, other types of garments used in other medical areas such as laboratories as well as laundry bags and other such containers all suffer from the same deficiencies and/or high costs.